#include<iostream>

using namespace std;

int main()
{
    int a = 10;
    int  b = 20;
    
    const int *p = &a;
    // *p = 20;
    p = &b;
    
    int * const p1 = &a;
    *p1 = 20;
    // p1 = &b;
    
    const int * const p2 = &a;
    // *p2 = 20;
    // p2 = &b;
    
    return 0;
    
}